1. Field of the Invention
The invention relates to a method of protecting plants against both plant pathogenic fungal organisms and mites on applying a single type of chemical effective against both the fungi and the mites.
2. Description of the Prior Art
Chemical agents which are effective against both plant pathogenic fungal organisms and mites at the same application dose rate are believed to be rare. Tricyclohexyl tin compounds such as those described in U.S. Pat. No. 3,264,177 are effective miticides but have very low if any fungicidal activity at miticidal dosage rates. Bis-(triorganotin) sulfates and sulfites, including such tricycloalkyl tin compounds as tricyclopentyl tins, tricyclohexyl tins and tricyclooctyl tin compounds are described broadly in U.S. Pat. No. 3,391,174 as having antifungal, bacteriostatic, nematocidal, miticidal and insecticidal activities. Other tricyclopentyl tin compounds have been prepared and described as having antifungal activity, but so far as is known there has been no suggestion that such compounds also have miticidal activity when applied to plants at effective antifungal dose rates and in less than seriously harmful phytotoxic amounts.
Some of the compounds used according to the invention described herein are old and others are new. The methodsa of preparation of the tricycloalkyl tin compounds are generally known. For example, tri(cyclopentyl) tin and tri(cyclopentylalkyl) tin halides wherein the halogen is chlorine, bromine or iodine can be prepared by reacting at least 3 moles of the corresponding cyclopentyl or cyclopentylalkyl magnesium halide with one mole of an alkyl tin trihalide. The resultant tetraorgano tin compound is reacted with an equimolar amount of a second tetravalent tin compound wherein the groups on the tin are each a group to serve as a counter ion in the desired product compound. During the reaction, one of the lower alkyl groups present on the tetraorgano tin compound is replaced by one of the groups from the second tetravalent tin compound. The reactions may be represented as follows: EQU 3-cyclopentylMgX+RSnY.sub.3 =(cyclopentyl).sub.3 SnR+3MgXY(cyclopentyl).sub.3 SnR+SnZ.sub.4 =(cyclopentyl).sub.3 SnZ+RSnZ.sub.3
wherein X and Y each independently represent chlorine, bromine or iodine, R is lower alkyl and Z is a functional group selected from, e.g., hydroxyl, bromine, chlorine, iodine, ##STR1##
The preparation should be carried out under anhydrous conditions at from ambient to slightly elevated temperatures and in an aprotic hydrocarbon solvent. The preparation of alkyl tin trihalides is described in U.S. Pat. No. 3,340,283. The reaction conditions which may be employed will be better understood with reference to the comprehensive treatment in an article by R. K. Ingham et al. appearing in the October 1960 issue of Chemical Reviews at pages 459-539.
The preparation of tricycloalkyl tin halides is also described in U.S. Pat. No. 3,595,892. Other compounds than the halides may be similarly prepared.
Further reference is made to Berichte der deutschen chemischen Gesellschaft 47, 3257-66 (1914); ibid., 57B, 532-44 (1924); British Pat. No. 760,056; and French Pat. No. 1,253,725; wherein are described methods of preparing tricyclohexyl tin compounds by methods which are generally applicable to the preparation of the present tricyclopentyl tin and tricyclopentylmethyl tin compounds.